Kubeletto
Deploy Guide · Java

Deploy a Spring Boot App

Ship your Spring Boot API without managing JVM servers.

Start Deploying Free Read the Docs

Overview

Spring Boot is the dominant Java framework for building production-grade microservices and REST APIs. Kubeletto runs your Spring Boot JAR in a containerized JVM, manages TLS and routing externally, and scales instances to zero when traffic drops — ideal for internal APIs and staging environments.

Prerequisites

  • A Spring Boot project with Maven or Gradle
  • application.properties or application.yml reading from environment variables
  • A Kubeletto account

Step-by-Step Guide

Deploying Spring Boot to Kubeletto is done by configuring a Dockerfile, connecting your GitHub repository, and setting environment variables. Follow this step-by-step checklist to deploy your code:

  1. 1

    Create a Dockerfile

    Use a multi-stage build to compile and package a minimal JRE runtime.

    dockerfile 
    FROM maven:3.9-eclipse-temurin-21 AS builder
WORKDIR /app
COPY pom.xml .
RUN mvn dependency:go-offline
COPY src ./src
RUN mvn package -DskipTests

FROM eclipse-temurin:21-jre-alpine
WORKDIR /app
COPY --from=builder /app/target/*.jar app.jar
EXPOSE 8080
ENTRYPOINT ["java", "-jar", "app.jar"]
  2. 2

    Read config from environment

    Spring Boot reads environment variables automatically for property overrides.

    properties 
    # application.properties
spring.datasource.url=${DATABASE_URL}
spring.datasource.username=${DB_USER}
spring.datasource.password=${DB_PASS}
server.port=${PORT:8080}
  3. 3

    Deploy to Kubeletto

    Set your database credentials and deploy.

    bash 
    kubeletto env set DATABASE_URL=jdbc:postgresql://host:5432/dbname --app spring-app
kubeletto env set DB_USER=user --app spring-app
kubeletto env set DB_PASS=password --app spring-app
kubeletto deploy --source github --repo your-org/spring-app --branch main

Sample Environment Variables

To configure your Spring Boot application, set these key-value pairs in the environment variables tab of the Kubeletto console or CLI. Ensure production secrets are flagged as write-only:

.env 
SERVER_PORT=8080
DATABASE_URL=jdbc:postgresql://host:5432/dbname
DB_USER=myuser
DB_PASS=mypassword
SPRING_PROFILES_ACTIVE=production
JAVA_TOOL_OPTIONS=-Xmx512m

Related Kubeletto Features

Kubeletto offers automatic SSL certificate provisioning, zero-downtime rollbacks, and scale-to-zero autoscaling for Spring Boot container workloads:

Docker Image Deploy App Metrics Automatic Scaling

PaaS Platform Comparisons

See how Kubeletto compares directly against other cloud platforms and PaaS providers when deploying Java workloads:

Kubeletto vs Railway Compare serverless Java deployment workflows and scale-to-zero pricing models. Kubeletto vs Render Compare container resource allocations, deploy speeds, and TLS setup for Java.

Frequently Asked Questions

Find direct answers to common questions about hosting, building, scaling, and managing Spring Boot containerized apps on Kubeletto:

How do I tune JVM memory for containers?

Set JAVA_TOOL_OPTIONS=-Xmx512m to cap heap usage. Kubeletto enforces a container memory limit, so always set -Xmx below the limit to avoid OOMKill.

Does Spring Boot Actuator work on Kubeletto?

Yes. Expose actuator on a separate management port or path and use it for health checks. Kubeletto's ingress routes all traffic to your main server.port.

Can I use GraalVM native image with Kubeletto?

Yes. Build a native image with GraalVM in your multi-stage Dockerfile. The resulting binary starts in milliseconds, making it ideal for scale-to-zero deployments.

More Deploy Guides

Go Deploy a Go Application Node.js Deploy a Node.js App Python Deploy a FastAPI App

Deploy your Spring Boot app today

Free during our active beta. No credit card required.

Start Deploying Free